48 BULLETIN OF THE 



lanceolate above, generally palmately trinerved, teeth of the borders large, 

 equal, sharply pointed. 13 specimens. 



41. P. Nebrascensis, var. longifolia, Lx. Leaves large, oblong-ovate, rounded 

 at base, five-nerved ; lateral primary nerves ascending to above the middle, 

 scarcely curved inside, much branching ; secondary nerves three or four pairs, 

 at a great distance from the base, camptodrome or craspedodrome, with their 

 divisions effaced at the borders which are cut in obtuse large teeth. The leaves 

 are longer, lanceolate from below the middle, 7^ to 11 cm. long, 4 to 7 cm. 

 broad below the middle ; the teeth are large, roimd, equal, marked from near 

 the base ; the petiole is long and slender. 15 specimens. 



42. Pofulus tenuinervata, sp. nov. Leaves comparatively small, rouud or 

 ovate, broadly cuneate or rounded at base, palmately five-nerved ; inner pri- 

 mary nerves cur\ing inward and ascending near the apex ; those of the out- 

 side also curving and ascending to the middle, all camptodrome, thin but 

 distinct ; borders irregularly dentate, the teeth unequal and pointed ; nervillea 

 distinct, obliquely joined in the middle. 



The leaves resemble those of a Ficus, being, in their facies, like those'of Ficus 

 crenata, Ung., which, however, has not distinct nervilles. They have a still 

 more marked likeness to those of Populus latior-tratisversa, Heer, as figured 

 by Ludwig in Paleont., V., Plate XXVI. fig. 3. The petiole is thick. 34 

 specimens. 



43. PopHliis crenata, Ung., considered by Schimper a var. of P. mutabilis, 

 Heer. The leaves are referable to the species as it is figured by the author, 

 Fl. of Sotzka, Plate XV. fig. 6, being small, oval, rounded, and trinerved at 

 base, the primary lateral nerves at an acute angle of divergence, not much 

 curved inward, the borders with large unequal teeth, the substance coriaceous 

 and the surface polished. 17 specimens. 



44. Populus attenvAita, Al. Br. 2 specimens. 



Plataneae. 



45 and 46. Platanus Guillelmce, Goepp., and P. aceroides, Heer. It is ex- 

 tremely difficult to separate the species. The description, of Heer, Fl. Alask., 

 p. 473, merely defines the leaves of P. GuillelnuB as undivided or merely sub- 

 lobate, acutely dentate, narrowed into a short petiole ; secondary nerves at an 

 acute angle of divergence ; and he remarks in the explanation, that the leaves 

 of Disco which he refers to the species are tapering to the petiole, slightly lobed 

 or not at all, and have short teeth. According to this, most of the very numer- 

 ous specimens obtained at Golden are referable to P. Guillelm.<B. I refer to 

 p. aceroide those with more open primary lateral nerves and of a more solid 

 consistence. The determination is rendered more uncertain by the generally 

 fragmentary state of the specimens. 76 specimens. 



47. Platanus Haydenii, Newby. A beautiful specimen, No. 508 of the list, 

 appears referable as a variety to this species. The leaf is oval in outline, tri- 

 nerved from above the decurring base ; the lobes, five, short, obtuse at the apex 



